In recent years, developments in displays present a development trend of high integrity and low cost. A very important technique among the developments is an implementation for mass production of GOA (Gate Driver on Array) technique. A gate switching circuit is integrated on an array substrate of a display panel by using the GOA technique to form a scan driving of the display panel, so that a gate driving integrate circuit part may be omitted. Thus, product cost may be reduced in terms of both material cost and manufacture process cost, and the display panel may be designed aesthetically with symmetrical sides and thin frame. Also, it benefits productivity and yield enhancement since a process for bonding in a gate direction may be omitted. The gate switching circuit integrated on the array substrate by using the GOA technique is also referred to as a GOA circuit or a shift register circuit. In addition, among current designs of mobile products, a GOA circuit with a bi-directional scan has become a focus of customer needs.
A bi-directional scan shift register circuit comprises several shift register units, each of the shift register units corresponds to one gate line. Specifically, an output terminal of each of the shift register units is connected with one gate line and the output terminal of a shift register unit is connected to an input terminal of a next shift register unit, except the first shift register unit and the last shift register unit. Each shift register unit in a traditional bi-directional scan shift register circuit has a 10TFT (Thin Film Transistor) 1Cap (capacitor) structure. The inventor found that, in the shift register with such a structure, a gate voltage at a gate driving TFT is pulled-up by a signal clock at a source of the gate driving TFT when a STV (Frame Start) signal is input, because the gate driving TFR has a large parasitic capacitance, which causes a capacitive coupling of the output signal of the shift register unit and then generates an abnormal output, and in turn a H-line Mura, i.e. a phenomenon in which light lines and dark lines appear alternately in a horizontal direction in a gray scale state when the display panel is lighted normally, occurs in the display panel.